It has basically no features. It's barely better than the commenting system on a blog.
Wouldnt it be cheaper to create plugins that add features instead of creating a new forum system entirely?
Not really. It's written in rails, which can be really buggy and has had major security issues in the past (I believe btcjam.com suffered from a hack due to an exploit in ruby on rails).
There used to be a hilarious issue with the way it handled session cookies, there was no cookie database. It used to simply delete the cookie off the browser when you hit "logout" but not delete them on the server, so if a hacker got your session cookie he could stay logged in as you forever even after you changed your password or hit logout. This issue was marked as a wontfix by the devs when it was discovered and stayed like that for years (since 2007 up till atleast 2013), though I don't know if it has been fixed:
http://threatpost.com/security-issue-in-ruby-on-rails-could-expose-cookies/102413The new forum is written in node.js IIRC, which is probably the best for a forum.
